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29 Sep, 2008

LID – Low-Impact Development

Posted by: Skylar In: Stormwater

Low-impact development is an approach to stormwater management where the watershed under post-development conditions is made as close as possible to the pre-development properties.  This requires the stormwater design to include various methods that manage stormwater quantity and quality in a natural manner.  In their article “Understanding LID”, stormh2o.com talks about the common errors in LID design:

In some cases, the so-called LID techniques are applied piecemeal with little consideration for the overall hydrology of the watershed. The original LID practices—developed over several decades, largely in Prince George’s County, MD—are now sometimes treated as a menu of choices: pick one from column A, two from column B, and you can say you have a “sustainable site.”

It’s important to consider the impact of every stormwater management technique used throughout the design of development areas.  It’s also important to consider factors like the soil’s infiltration potential, water table depth, and land uses to choose an adequate stormwater management solution.

One of the more common “green” stormwater solutions is bioretention (or rain gardens).  Stormh2o.com also has a good article titled “A Paradox of Nature”, which talks about the factors that should be considered in the design of rain gardens.  The article focuses a lot on the vegetation that should be planted within a rain garden, and the possibilities for using rain gardens as both practical and asthetic designs for landscape architects.  This helps with one of the more common complaints about bioretention areas:

Attractive and functional rain gardens are the exception, not the rule. Most rain garden installations do not include those elements that are culturally accepted as beautiful, like lush green lawns, flowering vegetation throughout the growing season, clean lines, and a maintained appearance. As a result, people see these landscapes as cluttered, unkempt, and unmanaged. Perceptions are just as important as environmental performance. If rain gardens are not perceived as attractive, cared-for environments, they will not be adopted during the design phase or managed after installation. Although preferences vary from person to person, a common theme for all is an appearance that communicates care to the viewer.

Rain gardens, or bioretention ponds, have been gaining quite a bit of attention in the wake of LEED buildings and sustainable design.  This article is a good read for those who would like to know more about designing this type of sustainable stormwater management solution.

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